Hi everyone, I'm new to the blur busters forums so I don't know if I post this on the right place.

I bought myself a monitor ~3 months ago, the Samsung LC27HG70 with Freesync. I am really happy of the monitor, the colors are so good, the contrast is amazing and all that. But, there is a big big issue with this monitor, the way that Overdrive is managed. Effectively, it can't be disabled, and under 120 Hz, the monitor get horrible reverse ghosting and is simply unusable, so it goes without saying but freesync technology is unusable too. And even if at 144 Hz the reverse ghosting is low, it is there and in dark areas in games it is annoying.

The fact is that I'm student in electronic engineering and I tried to get some information on the internet to know what type of scaler is used in the monitor, what hardware, because I would like to mod the firmware and disable completely the Overdrive to use freesync. But I didn't find any information useful, Samsung is totally deaf, and I posted here because I saw that firmware on some BenQ monitors had been customized, so I am wondering if someone has ideas, skills, or something to help.

Thanks in advance to all the community !(please excuse my english mistakes I'm french)

jojolapin102 wrote:Hi everyone, I'm new to the blur busters forums so I don't know if I post this on the right place.

I bought myself a monitor ~3 months ago, the Samsung LC27HG70 with Freesync. I am really happy of the monitor, the colors are so good, the contrast is amazing and all that. But, there is a big big issue with this monitor, the way that Overdrive is managed. Effectively, it can't be disabled, and under 120 Hz, the monitor get horrible reverse ghosting and is simply unusable, so it goes without saying but freesync technology is unusable too. And even if at 144 Hz the reverse ghosting is low, it is there and in dark areas in games it is annoying.

The fact is that I'm student in electronic engineering and I tried to get some information on the internet to know what type of scaler is used in the monitor, what hardware, because I would like to mod the firmware and disable completely the Overdrive to use freesync. But I didn't find any information useful, Samsung is totally deaf, and I posted here because I saw that firmware on some BenQ monitors had been customized, so I am wondering if someone has ideas, skills, or something to help.

Firstly, welcome to Blur Busters Forums!

Modifying the monitor firmware is extremely difficult and often costs more time than the purchase of a new monitor. It sometimes requires jailbreaking the monitor firmware, and there's a very small market for that (unlike phones) since discovering the cracks and reverse engineering needed can take more time than a university semester if you're not familiar with the process.

However, since you're an electronics engineering student helps, and if you've got a few disposable monitors, it's quite useful to try to disassemble the firmwares. The most common devices for monitor firmwares is an MSTAR ISP device but the code is often very monitor specific and requires getting darn near-impossible-to-access specsheets. Big brandname monitors are often more opaque than generics that may have a much more easily rewriteable firmware (and/or bootloader).

The best bet is to try to find a variable called "OD Gain" which is often a value from 0 to 100 or 0 to 255. This may be found in things like "Factory Menu", "Service Menu" or accessible via a utility called Entech SoftMCCS (may have to experiment with manufacturer-specific VCP codes 0xE0 through 0xFF to figure out if one of them maps to overdrive gain). This will increase/decrease the reverse ghosting.

Next, I should mention that VA panels are very heat-sensitive so if it is winter in your country, please heat-up the VA panel to approximately 20 degrees C throughout its entire surface before deciding if it's worth the effort to calibrate overdrive. Cold VA panels will ghost much more than warmed-up VA panels as well.

Also, I've some VA panels have automatic overdrive-gain increase/decrease controlled by thermosistor (temperature) because of this reason. I'm not 100% sure, but I saw this behavior on an Eizo FG2421. If your Samsung is one of them, make sure to warm up for 30 minutes to see if any automatic OD gain adjustments spontaneously occur.

Modifying the monitor firmware is extremely difficult and often costs more time than the purchase of a new monitor. It sometimes requires jailbreaking the monitor firmware, and there's a very small market for that (unlike phones) since discovering the cracks and reverse engineering needed can take more time than a university semester if you're not familiar with the process.

However, since you're an electronics engineering student helps, and if you've got a few disposable monitors, it's quite useful to try to disassemble the firmwares. The most common devices for monitor firmwares is an MSTAR ISP device but the code is often very monitor specific and requires getting darn near-impossible-to-access specsheets. Big brandname monitors are often more opaque than generics that may have a much more easily rewriteable firmware (and/or bootloader).

The best bet is to try to find a variable called "OD Gain" which is often a value from 0 to 100 or 0 to 255. This may be found in things like "Factory Menu", "Service Menu" or accessible via a utility called Entech SoftMCCS (may have to experiment with manufacturer-specific VCP codes 0xE0 through 0xFF to figure out if one of them maps to overdrive gain). This will increase/decrease the reverse ghosting.

Next, I should mention that VA panels are very heat-sensitive so if it is winter in your country, please heat-up the VA panel to approximately 20 degrees C throughout its entire surface before deciding if it's worth the effort to calibrate overdrive. Cold VA panels will ghost much more than warmed-up VA panels as well.

Also, I've some VA panels have automatic overdrive-gain increase/decrease controlled by thermosistor (temperature) because of this reason. I'm not 100% sure, but I saw this behavior on an Eizo FG2421. If your Samsung is one of them, make sure to warm up for 30 minutes to see if any automatic OD gain adjustments spontaneously occur.

Thanks very much for your complete answer !

Yeah I noticed that it's not funny and really difficult at all, but I would like to do that completely if it's even possible.Effectively, to study electronics helps a lot, I know how to control electronics systems and I have learned to program microcontrollers and FPGAs.

Unfortunately this is my only "normal" disposable monitor, I wish I had others but the monitor I had before had G-sync and this is not a common scaler.

When you talk about a variable you mean in the monitor firmware ? Because that's an horrible bin file, and I don't know if it's a memory configuration file for an FPGA for example, or a compiled file for a specific architecture. I've also tried Entech SoftMCCS software, which is really good and useful, but the problem is that manufacturer VPS codes are grayed out like in the image here : https://imgur.com/a/kan2mZ5

I saw on testufo that the blur is heavy on VA panels, and effectively when it is cold it' much more present, and overshoot is less here, but 30 minutes later the overshoot is here and ghosting less present. I don't know if its auto OD-gain but the overshoot is much more present when the monitor is hot.

jojolapin102 wrote:Yeah I noticed that it's not funny and really difficult at all, but I would like to do that completely if it's even possible. Effectively, to study electronics helps a lot, I know how to control electronics systems and I have learned to program microcontrollers and FPGAs.

Unfortunately this is my only "normal" disposable monitor, I wish I had others but the monitor I had before had G-sync and this is not a common scaler.

When you talk about a variable you mean in the monitor firmware ? Because that's an horrible bin file, and I don't know if it's a memory configuration file for an FPGA for example, or a compiled file for a specific architecture.

Compiled for a specific architecture, whatever chip the monitor firmware uses. So you need to figure out what chip architecture it is before you can remotely begin to disassemble it. Some of the files are encrypted but view them in a hexeditor and you may see strings like on-screen menus, and embedded resources like boot-up bitmaps and such.

jojolapin102 wrote:I've also tried Entech SoftMCCS software, which is really good and useful, but the problem is that manufacturer VPS codes are grayed out like in the image here : https://imgur.com/a/kan2mZ5

This is manufacturer-dependant. They are greyed out if they're not in use (e.g. readonly registers).

jojolapin102 wrote:I saw on testufo that the blur is heavy on VA panels, and effectively when it is cold it' much more present, and overshoot is less here, but 30 minutes later the overshoot is here and ghosting less present. I don't know if its auto OD-gain but the overshoot is much more present when the monitor is hot.

If you see a gradual decrease as monitor warms up, it's likely not thermosistor-controlled overdrive gain -- it's just warm LCDs responds faster. You know when you leave your smartphone in a freezing car or accidentally forget it outdoors (or put it in the freezer for half an hour), you'll notice the screen will ghost really badly when freezing cold. And starts ghosting less and less as the screen warms up. That is normal for LCD.

VA is particularly sensitive to this, to the point where a few degrees of warming up can actually make a big difference in ghosting behaviour for a VA panel.

If the overdrive was tuned at a colder temperature, the coronas can actually get worse when the monitor is hot. Manufacturer overdrive tuning should be done in environments matching end users.

The effects can be different in a corner of the monitor (e.g. where the hot power supply is) -- e.g. different ghosting in a corner of a monitor. This is often overlooked by many monitor manufacturers, that temperature differentials can be bad.

Heating filaments can be built into the monitor to try to warm up the panel to an exact temperature for the most perfect zero-ghosting possible (for VA), but I don't know any monitor manufacturers that do this.

This even interferes with input lag tests, since input lag tests have to stop the latency stopwatch somewhere along the GtG curve (e.g. GtG10% or GtG50% or GtG90%)

Chief Blur Buster wrote:Compiled for a specific architecture, whatever chip the monitor firmware uses. So you need to figure out what chip architecture it is before you can remotely begin to disassemble it. Some of the files are encrypted but view them in a hexeditor and you may see strings like on-screen menus, and embedded resources like boot-up bitmaps and such.

I recently managed to get in the service menu of the monitor, I have the Scaler model, MSTAR MST9804, but there is nothing about it on the internet. Unfortunately, there was no setting like OD gain in the service menu, just the language, the number of hours that the panel is in use, and nothing interesting. I also tried to open and view firmware updates files in a hexeditor, but there was nothing really interesting unfortunately.

Chief Blur Buster wrote:If you see a gradual decrease as monitor warms up, it's likely not thermosistor-controlled overdrive gain -- it's just warm LCDs responds faster. You know when you leave your smartphone in a freezing car or accidentally forget it outdoors (or put it in the freezer for half an hour), you'll notice the screen will ghost really badly when freezing cold. And starts ghosting less and less as the screen warms up. That is normal for LCD.

That's exactly what I see every time, that's pretty annoying because when the monitor is cold and at 144 Hz, there is just normal ghosting but not too much, and when it warms up the overshoot appears.

Chief Blur Buster wrote:VA is particularly sensitive to this, to the point where a few degrees of warming up can actually make a big difference in ghosting behaviour for a VA panel.

If the overdrive was tuned at a colder temperature, the coronas can actually get worse when the monitor is hot. Manufacturer overdrive tuning should be done in environments matching end users.

The effects can be different in a corner of the monitor (e.g. where the hot power supply is) -- e.g. different ghosting in a corner of a monitor. This is often overlooked by many monitor manufacturers, that temperature differentials can be bad.

Heating filaments can be built into the monitor to try to warm up the panel to an exact temperature for the most perfect zero-ghosting possible (for VA), but I don't know any monitor manufacturers that do this.

This even interferes with input lag tests, since input lag tests have to stop the latency stopwatch somewhere along the GtG curve (e.g. GtG10% or GtG50% or GtG90%)

I think you're right, they tuned the overdrive in a cool room, and only for 144 Hz, such a bad job

Thanks very much for all your answers, I'll see what I can do, but probably nothing.